It isn't for me. Is there a situation where it isn't stored? Such as drag and drop via browser (Brave Browser)?

Ok, I inspected the database using the SQLite viewer plugin in VSCode.

# Inspect file structure inside volume
docker run --rm -it -v paperless-test_paperless_config:/data busybox ls -lah /data

# Copy database out for manual inspection
docker run --rm \
  -v paperless-test_paperless_config:/data \
  -v "$(pwd)":/host \
  busybox cp /data/db.sqlite3 /host/db.sqlite3

I'm not sure what table to expect this data in but I found the original names listed in table documents_paperlesstask column name. The original directory path seems lost when a directory was dragged/dropped on the UI.

Table documents_document only contains the Paperless assigned filename. The question remains, why it isn't showing in the UI. I couldn't find the other xmp metadata in the table. Where do you expect this data in the db for it to show in the UI?